Effect of structures on rheology in a model magnetorheological fluid

The structure dependence of rheology on a model magnetorheological fluid is investigated experimentally. We find that the column-dominated structure f ormed under slow ramping of the magnetic field has higher dynamic yield str ess than the "bent-wall" dominated structure formed under the fast tamping field. The: measurement of the shear rate loop under fast tamping shows an abnormal rheological hysteresis. It indicates a shear assisted structural t ransition from the "bent-wall" dominated structure to a more stable structu re. A possible shear-induced structure with circular stripes is suggested.